#include <sys/ioctl.h>
#include <termios.h>
#include <unistd.h>
#include <string.h>
#include <stdio.h>
#include "tty.h"

#define ANSI_BOLD_ON       "1"
#define ANSI_BOLD_OFF      "22"
#define ANSI_ITALIC_ON     "3"
#define ANSI_ITALIC_OFF    "23"
#define ANSI_UNDERLINE_ON  "4"
#define ANSI_UNDERLINE_OFF "24"

#define ANSI_DEFAULTCOLOUR_FG "39"
#define ANSI_DEFAULTCOLOUR_BG "49"

#define ANSI_256COLOUR_FG "38;5"
#define ANSI_256COLOUR_BG "48;5"

#define ANSI_TRUECOLOUR_FG "38;2"
#define ANSI_TRUECOLOUR_BG "48;2"

enum tty_flags {
	TTY_INIT = 0x01u,
	TTY_INTERACTIVE = 0x02u,
};

struct s_tty {
	FILE *t_in, *t_out;
	enum tty_flags t_flags;
	struct termios t_ios_raw, t_ios_default;
	struct s_tty_vmode t_vmode;
	unsigned char t_mcount;
};

static struct s_tty tty = {};

static const char *ansi_colour16_fg[] = {
	[TTY_COLOUR16_BLACK]          = "30",
	[TTY_COLOUR16_RED]            = "31",
	[TTY_COLOUR16_GREEN]          = "32",
	[TTY_COLOUR16_YELLOW]         = "33",
	[TTY_COLOUR16_BLUE]           = "34",
	[TTY_COLOUR16_MAGENTA]        = "35",
	[TTY_COLOUR16_CYAN]           = "36",
	[TTY_COLOUR16_WHITE]          = "37",
	[TTY_COLOUR16_GREY]           = "90",
	[TTY_COLOUR16_BRIGHT_RED]     = "91",
	[TTY_COLOUR16_BRIGHT_GREEN]   = "92",
	[TTY_COLOUR16_BRIGHT_YELLOW]  = "93",
	[TTY_COLOUR16_BRIGHT_BLUE]    = "94",
	[TTY_COLOUR16_BRIGHT_MAGENTA] = "95",
	[TTY_COLOUR16_BRIGHT_CYAN]    = "96",
	[TTY_COLOUR16_BRIGHT_WHITE]   = "97",
};

static const char *ansi_colour16_bg[] = {
	[TTY_COLOUR16_BLACK]          = "40",
	[TTY_COLOUR16_RED]            = "41",
	[TTY_COLOUR16_GREEN]          = "42",
	[TTY_COLOUR16_YELLOW]         = "43",
	[TTY_COLOUR16_BLUE]           = "44",
	[TTY_COLOUR16_MAGENTA]        = "45",
	[TTY_COLOUR16_CYAN]           = "46",
	[TTY_COLOUR16_WHITE]          = "47",
	[TTY_COLOUR16_GREY]           = "100",
	[TTY_COLOUR16_BRIGHT_RED]     = "101",
	[TTY_COLOUR16_BRIGHT_GREEN]   = "102",
	[TTY_COLOUR16_BRIGHT_YELLOW]  = "103",
	[TTY_COLOUR16_BRIGHT_BLUE]    = "104",
	[TTY_COLOUR16_BRIGHT_MAGENTA] = "105",
	[TTY_COLOUR16_BRIGHT_CYAN]    = "106",
	[TTY_COLOUR16_BRIGHT_WHITE]   = "107",
};

static void init_tty(struct s_tty *tty, FILE *in, FILE *out)
{
	tty->t_in = in;
	tty->t_out = out;

	int fd = fileno(in);

	if (isatty(fd)) {
		tty->t_flags |= TTY_INTERACTIVE;
	}

	tcgetattr(fd, &tty->t_ios_default);
	memcpy(&tty->t_ios_raw, &tty->t_ios_default, sizeof tty->t_ios_raw);

	tty->t_ios_raw.c_iflag &= ~(ICRNL | IXON);
	tty->t_ios_raw.c_oflag &= ~(OPOST);
	tty->t_ios_raw.c_lflag &= ~(ECHO | ICANON | IEXTEN);

	tty->t_flags |= TTY_INIT;
}

struct s_tty *s_get_tty(void)
{
	if (!(tty.t_flags & TTY_INIT)) {
		init_tty(&tty, stdin, stdout);
	}

	return &tty;
}

bool s_tty_is_interactive(const struct s_tty *tty)
{
	return (tty->t_flags & TTY_INTERACTIVE) == TTY_INTERACTIVE;
}

void s_tty_set_raw(struct s_tty *tty)
{
	tcsetattr(STDIN_FILENO, TCSAFLUSH, &tty->t_ios_raw);
}

void s_tty_set_canon(struct s_tty *tty)
{
	tcsetattr(STDIN_FILENO, TCSAFLUSH, &tty->t_ios_default);
}

void s_tty_reset_vmode(struct s_tty *tty)
{
	if (tty->t_vmode.v_fg.c_mode == TTY_COLOUR_NONE
		       	&& tty->t_vmode.v_bg.c_mode == TTY_COLOUR_NONE
		       	&& tty->t_vmode.v_attrib == TTY_ATTRIB_NORMAL) {
		return;
	}

	fprintf(tty->t_out, "\033[0;39;49m");

	memset(&tty->t_vmode, 0x0, sizeof tty->t_vmode);

	tty->t_vmode.v_fg.c_mode = TTY_COLOUR_NONE;
	tty->t_vmode.v_bg.c_mode = TTY_COLOUR_NONE;
	tty->t_vmode.v_attrib = TTY_ATTRIB_NORMAL;
}

static int compare_colour(const struct s_tty_colour *a, const struct s_tty_colour *b)
{
	if (a->c_mode != b->c_mode) {
		return -1;
	}

	switch (a->c_mode) {
	case TTY_COLOUR_16:
		if (a->c_16.value != b->c_16.value) {
			return -1;
		}
		break;
	case TTY_COLOUR_256:
		if (a->c_256.value != b->c_256.value) {
			return -1;
		}
		break;
	case TTY_COLOUR_TRUE:
		if (a->c_true.r != b->c_true.r) {
			return -1;
		}

		if (a->c_true.g != b->c_true.g) {
			return -1;
		}

		if (a->c_true.b != b->c_true.b) {
			return -1;
		}
		break;
	default:
		break;
	}

	return 0;
}

static int compare_vmode(const struct s_tty_vmode *a, const struct s_tty_vmode *b)
{
	if (a->v_attrib != b->v_attrib) {
		return -1;
	}

	if (compare_colour(&a->v_fg, &b->v_fg) != 0) {
		return -1;
	}

	if (compare_colour(&a->v_bg, &b->v_bg) != 0) {
		return -1;
	}

	return 0;
}

static void put_ansi_attrib(struct s_tty *tty, const char *s)
{
	if (tty->t_mcount > 0) {
		fputs(";", tty->t_out);
	}

	fputs(s, tty->t_out);
	tty->t_mcount++;
}

static void set_attrib(struct s_tty *tty, enum s_tty_attrib old, enum s_tty_attrib new)
{
	if (old == new) {
		return;
	}

	/* Bold ON */
	if (!(old & TTY_ATTRIB_BOLD) && new & TTY_ATTRIB_BOLD) {
		put_ansi_attrib(tty, ANSI_BOLD_ON);
	}

	/* Bold OFF */
	if (old & TTY_ATTRIB_BOLD && !(new & TTY_ATTRIB_BOLD)) {
		put_ansi_attrib(tty, ANSI_BOLD_OFF);
	}

	/* Underline ON */
	if (!(old & TTY_ATTRIB_UNDERLINE) && new & TTY_ATTRIB_UNDERLINE) {
		put_ansi_attrib(tty, ANSI_UNDERLINE_ON);
	}

	/* Underline OFF */
	if (old & TTY_ATTRIB_UNDERLINE && !(new & TTY_ATTRIB_UNDERLINE)) {
		put_ansi_attrib(tty, ANSI_UNDERLINE_OFF);
	}

	/* Italic ON */
	if (!(old & TTY_ATTRIB_ITALIC) && new & TTY_ATTRIB_ITALIC) {
		put_ansi_attrib(tty, ANSI_ITALIC_ON);
	}

	/* Italic OFF */
	if (old & TTY_ATTRIB_ITALIC && !(new & TTY_ATTRIB_ITALIC)) {
		put_ansi_attrib(tty, ANSI_ITALIC_OFF);
	}
}

static void set_fg(struct s_tty *tty, const struct s_tty_colour *old, const struct s_tty_colour *new)
{
	if (compare_colour(old, new) == 0) {
		return;
	}

	char buf[8];

	switch (new->c_mode) {
	case TTY_COLOUR_NONE:
		put_ansi_attrib(tty, ANSI_DEFAULTCOLOUR_FG);
		break;
	case TTY_COLOUR_16:
		put_ansi_attrib(tty, ansi_colour16_fg[new->c_16.value]);
		break;
	case TTY_COLOUR_256:
		put_ansi_attrib(tty, ANSI_256COLOUR_FG);
		snprintf(buf, sizeof buf, "%u", new->c_256.value);
		put_ansi_attrib(tty, buf);
		break;
	case TTY_COLOUR_TRUE:
		put_ansi_attrib(tty, ANSI_TRUECOLOUR_FG);
		snprintf(buf, sizeof buf, "%u", new->c_true.r);
		put_ansi_attrib(tty, buf);
		snprintf(buf, sizeof buf, "%u", new->c_true.g);
		put_ansi_attrib(tty, buf);
		snprintf(buf, sizeof buf, "%u", new->c_true.b);
		put_ansi_attrib(tty, buf);
		break;
	default:
		break;
	}
}

static void set_bg(struct s_tty *tty, const struct s_tty_colour *old, const struct s_tty_colour *new)
{
	if (compare_colour(old, new) == 0) {
		return;
	}

	char buf[8];

	switch (new->c_mode) {
	case TTY_COLOUR_NONE:
		put_ansi_attrib(tty, ANSI_DEFAULTCOLOUR_BG);
		break;
	case TTY_COLOUR_16:
		put_ansi_attrib(tty, ansi_colour16_bg[new->c_16.value]);
		break;
	case TTY_COLOUR_256:
		put_ansi_attrib(tty, ANSI_256COLOUR_BG);
		snprintf(buf, sizeof buf, "%u", new->c_256.value);
		put_ansi_attrib(tty, buf);
		break;
	case TTY_COLOUR_TRUE:
		put_ansi_attrib(tty, ANSI_TRUECOLOUR_BG);
		snprintf(buf, sizeof buf, "%u", new->c_true.r);
		put_ansi_attrib(tty, buf);
		snprintf(buf, sizeof buf, "%u", new->c_true.g);
		put_ansi_attrib(tty, buf);
		snprintf(buf, sizeof buf, "%u", new->c_true.b);
		put_ansi_attrib(tty, buf);
		break;
	default:
		break;
	}
}

void s_tty_set_vmode(struct s_tty *tty, const struct s_tty_vmode *vmode)
{
	if (compare_vmode(&tty->t_vmode, vmode) == 0) {
		return;
	}

	tty->t_mcount = 0;

	fprintf(tty->t_out, "\033[");

	set_attrib(tty, tty->t_vmode.v_attrib, vmode->v_attrib);
	set_fg(tty, &tty->t_vmode.v_fg, &vmode->v_fg);
	set_bg(tty, &tty->t_vmode.v_bg, &vmode->v_bg);

	fprintf(tty->t_out, "m");

	memcpy(&tty->t_vmode, vmode, sizeof *vmode);
}

s_keycode s_tty_read_key(struct s_tty *tty)
{
	char c;
	int v;
	int fd = fileno(tty->t_in);

	while (1) {
		v = read(fd, &c, 1);
		if (v < 1) {
			return S_KEY_EOF;
		}

		if (c == '\r' || c == '\n') {
			return  S_KEY_RETURN;
		}

		if (c == '\b' || c == 0x7F) {
			return S_KEY_BACKSPACE;
		}

		if (c >= 1 && c <= 26) {
			return S_TTY_CTRL_KEY(c + 'a' - 1);
		}

		if (c != 0x1b) {
			return c;
		}

		v = read(fd, &c, 1);
		if (v < 1) {
			return S_KEY_EOF;
		}

		if (c != '[') {
			continue;
		}

		v = read(fd, &c, 1);
		if (v < 1) {
			return S_KEY_EOF;
		}

		switch (c) {
		case 'A':
			return S_KEY_ARROW_UP;
		case 'B':
			return S_KEY_ARROW_DOWN;
		case 'C':
			return S_KEY_ARROW_RIGHT;
		case 'D':
			return S_KEY_ARROW_LEFT;
		default:
			continue;
		}
	}

	return c;
}